/*
    SPDX-FileCopyrightText: 2008-2010 Michel Ludwig <michel.ludwig@kdemail.net>
    SPDX-FileCopyrightText: 2009 Joseph Wenninger <jowenn@kde.org>

    SPDX-License-Identifier: LGPL-2.0-or-later
*/
#include "ontheflycheck.h"

#include <QRegularExpression>
#include <QTimer>

#include "katebuffer.h"
#include "kateconfig.h"
#include "kateglobal.h"
#include "katepartdebug.h"
#include "kateview.h"
#include "spellcheck.h"
#include "spellingmenu.h"

#define ON_THE_FLY_DEBUG qCDebug(LOG_KTE)

namespace
{
inline const QPair<KTextEditor::MovingRange *, QString> &invalidSpellCheckQueueItem()
{
    static const auto item = QPair<KTextEditor::MovingRange *, QString>(nullptr, QString());
    return item;
}

}

KateOnTheFlyChecker::KateOnTheFlyChecker(KTextEditor::DocumentPrivate *document)
    : QObject(document)
    , m_document(document)
    , m_backgroundChecker(nullptr)
    , m_currentlyCheckedItem(invalidSpellCheckQueueItem())
    , m_refreshView(nullptr)
{
    ON_THE_FLY_DEBUG << "created";

    m_viewRefreshTimer = new QTimer(this);
    m_viewRefreshTimer->setSingleShot(true);
    connect(m_viewRefreshTimer, &QTimer::timeout, this, &KateOnTheFlyChecker::viewRefreshTimeout);

    connect(document, &KTextEditor::DocumentPrivate::textInsertedRange, this, &KateOnTheFlyChecker::textInserted);
    connect(document, &KTextEditor::DocumentPrivate::textRemoved, this, &KateOnTheFlyChecker::textRemoved);
    connect(document, &KTextEditor::DocumentPrivate::viewCreated, this, &KateOnTheFlyChecker::addView);
    connect(document, &KTextEditor::DocumentPrivate::highlightingModeChanged, this, &KateOnTheFlyChecker::updateConfig);
    connect(&document->buffer(), &KateBuffer::respellCheckBlock, this, &KateOnTheFlyChecker::handleRespellCheckBlock);

    connect(document, &KTextEditor::Document::reloaded, this, [this](KTextEditor::Document *) {
        refreshSpellCheck();
    });

    // load the settings for the speller
    updateConfig();

    const auto views = document->views();
    for (KTextEditor::View *view : views) {
        addView(document, view);
    }
    refreshSpellCheck();
}

KateOnTheFlyChecker::~KateOnTheFlyChecker()
{
    freeDocument();
}

QPair<KTextEditor::Range, QString> KateOnTheFlyChecker::getMisspelledItem(const KTextEditor::Cursor cursor) const
{
    for (const MisspelledItem &item : m_misspelledList) {
        KTextEditor::MovingRange *movingRange = item.first;
        if (movingRange->contains(cursor)) {
            return QPair<KTextEditor::Range, QString>(*movingRange, item.second);
        }
    }
    return QPair<KTextEditor::Range, QString>(KTextEditor::Range::invalid(), QString());
}

QString KateOnTheFlyChecker::dictionaryForMisspelledRange(KTextEditor::Range range) const
{
    for (const MisspelledItem &item : m_misspelledList) {
        KTextEditor::MovingRange *movingRange = item.first;
        if (*movingRange == range) {
            return item.second;
        }
    }
    return QString();
}

void KateOnTheFlyChecker::clearMisspellingForWord(const QString &word)
{
    const MisspelledList misspelledList = m_misspelledList; // make a copy
    for (const MisspelledItem &item : misspelledList) {
        KTextEditor::MovingRange *movingRange = item.first;
        if (m_document->text(*movingRange) == word) {
            deleteMovingRange(movingRange);
        }
    }
}

void KateOnTheFlyChecker::handleRespellCheckBlock(int start, int end)
{
    ON_THE_FLY_DEBUG << start << end;
    KTextEditor::Range range(start, 0, end, m_document->lineLength(end));
    bool listEmpty = m_modificationList.isEmpty();
    KTextEditor::MovingRange *movingRange = m_document->newMovingRange(range);
    movingRange->setFeedback(this);
    // we don't handle this directly as the highlighting information might not be up-to-date yet
    m_modificationList.push_back(ModificationItem(TEXT_INSERTED, movingRange));
    ON_THE_FLY_DEBUG << "added" << *movingRange;
    if (listEmpty) {
        QTimer::singleShot(0, this, &KateOnTheFlyChecker::handleModifiedRanges);
    }
}

void KateOnTheFlyChecker::textInserted(KTextEditor::Document *document, KTextEditor::Range range)
{
    Q_ASSERT(document == m_document);
    Q_UNUSED(document);
    if (!range.isValid()) {
        return;
    }

    bool listEmptyAtStart = m_modificationList.isEmpty();

    // don't consider a range that is not within the document range
    const KTextEditor::Range documentIntersection = m_document->documentRange().intersect(range);
    if (!documentIntersection.isValid()) {
        return;
    }
    // for performance reasons we only want to schedule spellchecks for ranges that are visible
    const auto views = m_document->views();
    for (KTextEditor::View *i : views) {
        KTextEditor::ViewPrivate *view = static_cast<KTextEditor::ViewPrivate *>(i);
        KTextEditor::Range visibleIntersection = documentIntersection.intersect(view->visibleRange());
        if (visibleIntersection.isValid()) { // allow empty intersections
            // we don't handle this directly as the highlighting information might not be up-to-date yet
            KTextEditor::MovingRange *movingRange = m_document->newMovingRange(visibleIntersection);
            movingRange->setFeedback(this);
            m_modificationList.push_back(ModificationItem(TEXT_INSERTED, movingRange));
            ON_THE_FLY_DEBUG << "added" << *movingRange;
        }
    }

    if (listEmptyAtStart && !m_modificationList.isEmpty()) {
        QTimer::singleShot(0, this, &KateOnTheFlyChecker::handleModifiedRanges);
    }
}

void KateOnTheFlyChecker::handleInsertedText(KTextEditor::Range range)
{
    KTextEditor::Range consideredRange = range;
    ON_THE_FLY_DEBUG << m_document << range;

    bool spellCheckInProgress = m_currentlyCheckedItem != invalidSpellCheckQueueItem();

    if (spellCheckInProgress) {
        KTextEditor::MovingRange *spellCheckRange = m_currentlyCheckedItem.first;
        if (spellCheckRange->contains(consideredRange)) {
            consideredRange = *spellCheckRange;
            stopCurrentSpellCheck();
            deleteMovingRangeQuickly(spellCheckRange);
        } else if (consideredRange.contains(*spellCheckRange)) {
            stopCurrentSpellCheck();
            deleteMovingRangeQuickly(spellCheckRange);
        } else if (consideredRange.overlaps(*spellCheckRange)) {
            consideredRange.expandToRange(*spellCheckRange);
            stopCurrentSpellCheck();
            deleteMovingRangeQuickly(spellCheckRange);
        } else {
            spellCheckInProgress = false;
        }
    }
    for (QList<SpellCheckItem>::iterator i = m_spellCheckQueue.begin(); i != m_spellCheckQueue.end();) {
        KTextEditor::MovingRange *spellCheckRange = (*i).first;
        if (spellCheckRange->contains(consideredRange)) {
            consideredRange = *spellCheckRange;
            ON_THE_FLY_DEBUG << "erasing range " << *i;
            i = m_spellCheckQueue.erase(i);
            deleteMovingRangeQuickly(spellCheckRange);
        } else if (consideredRange.contains(*spellCheckRange)) {
            ON_THE_FLY_DEBUG << "erasing range " << *i;
            i = m_spellCheckQueue.erase(i);
            deleteMovingRangeQuickly(spellCheckRange);
        } else if (consideredRange.overlaps(*spellCheckRange)) {
            consideredRange.expandToRange(*spellCheckRange);
            ON_THE_FLY_DEBUG << "erasing range " << *i;
            i = m_spellCheckQueue.erase(i);
            deleteMovingRangeQuickly(spellCheckRange);
        } else {
            ++i;
        }
    }
    KTextEditor::Range spellCheckRange = findWordBoundaries(consideredRange.start(), consideredRange.end());
    const bool emptyAtStart = m_spellCheckQueue.isEmpty();

    queueSpellCheckVisibleRange(spellCheckRange);

    if (spellCheckInProgress || (emptyAtStart && !m_spellCheckQueue.isEmpty())) {
        QTimer::singleShot(0, this, &KateOnTheFlyChecker::performSpellCheck);
    }
}

void KateOnTheFlyChecker::textRemoved(KTextEditor::Document *document, KTextEditor::Range range)
{
    Q_ASSERT(document == m_document);
    Q_UNUSED(document);
    if (!range.isValid()) {
        return;
    }

    bool listEmptyAtStart = m_modificationList.isEmpty();

    // don't consider a range that is behind the end of the document
    const KTextEditor::Range documentIntersection = m_document->documentRange().intersect(range);
    if (!documentIntersection.isValid()) { // the intersection might however be empty if the last
        return; // word has been removed, for example
    }

    // for performance reasons we only want to schedule spellchecks for ranges that are visible
    const auto views = m_document->views();
    for (KTextEditor::View *i : views) {
        KTextEditor::ViewPrivate *view = static_cast<KTextEditor::ViewPrivate *>(i);
        KTextEditor::Range visibleIntersection = documentIntersection.intersect(view->visibleRange());
        if (visibleIntersection.isValid()) { // see above
            // we don't handle this directly as the highlighting information might not be up-to-date yet
            KTextEditor::MovingRange *movingRange = m_document->newMovingRange(visibleIntersection);
            movingRange->setFeedback(this);
            m_modificationList.push_back(ModificationItem(TEXT_REMOVED, movingRange));
            ON_THE_FLY_DEBUG << "added" << *movingRange << view->visibleRange();
        }
    }
    if (listEmptyAtStart && !m_modificationList.isEmpty()) {
        QTimer::singleShot(0, this, &KateOnTheFlyChecker::handleModifiedRanges);
    }
}

inline bool rangesAdjacent(KTextEditor::Range r1, KTextEditor::Range r2)
{
    return (r1.end() == r2.start()) || (r2.end() == r1.start());
}

void KateOnTheFlyChecker::handleRemovedText(KTextEditor::Range range)
{
    ON_THE_FLY_DEBUG << range;

    QList<KTextEditor::Range> rangesToReCheck;
    for (QList<SpellCheckItem>::iterator i = m_spellCheckQueue.begin(); i != m_spellCheckQueue.end();) {
        KTextEditor::MovingRange *spellCheckRange = (*i).first;
        if (rangesAdjacent(*spellCheckRange, range) || spellCheckRange->contains(range)) {
            ON_THE_FLY_DEBUG << "erasing range " << *i;
            if (!spellCheckRange->isEmpty()) {
                rangesToReCheck.push_back(*spellCheckRange);
            }
            deleteMovingRangeQuickly(spellCheckRange);
            i = m_spellCheckQueue.erase(i);
        } else {
            ++i;
        }
    }
    bool spellCheckInProgress = m_currentlyCheckedItem != invalidSpellCheckQueueItem();
    const bool emptyAtStart = m_spellCheckQueue.isEmpty();
    if (spellCheckInProgress) {
        KTextEditor::MovingRange *spellCheckRange = m_currentlyCheckedItem.first;
        ON_THE_FLY_DEBUG << *spellCheckRange;
        if (m_document->documentRange().contains(*spellCheckRange) && (rangesAdjacent(*spellCheckRange, range) || spellCheckRange->contains(range))
            && !spellCheckRange->isEmpty()) {
            rangesToReCheck.push_back(*spellCheckRange);
            ON_THE_FLY_DEBUG << "added the range " << *spellCheckRange;
            stopCurrentSpellCheck();
            deleteMovingRangeQuickly(spellCheckRange);
        } else if (spellCheckRange->isEmpty()) {
            stopCurrentSpellCheck();
            deleteMovingRangeQuickly(spellCheckRange);
        } else {
            spellCheckInProgress = false;
        }
    }
    for (QList<KTextEditor::Range>::iterator i = rangesToReCheck.begin(); i != rangesToReCheck.end(); ++i) {
        queueSpellCheckVisibleRange(*i);
    }

    KTextEditor::Range spellCheckRange = findWordBoundaries(range.start(), range.start());
    KTextEditor::Cursor spellCheckEnd = spellCheckRange.end();

    queueSpellCheckVisibleRange(spellCheckRange);

    if (range.numberOfLines() > 0) {
        // FIXME: there is no currently no way of doing this better as we only get notifications for removals of
        //       of single lines, i.e. we don't know here how many lines have been removed in total
        KTextEditor::Cursor nextLineStart(spellCheckEnd.line() + 1, 0);
        const KTextEditor::Cursor documentEnd = m_document->documentEnd();
        if (nextLineStart < documentEnd) {
            KTextEditor::Range rangeBelow = KTextEditor::Range(nextLineStart, documentEnd);

            const QList<KTextEditor::View *> &viewList = m_document->views();
            for (QList<KTextEditor::View *>::const_iterator i = viewList.begin(); i != viewList.end(); ++i) {
                KTextEditor::ViewPrivate *view = static_cast<KTextEditor::ViewPrivate *>(*i);
                const KTextEditor::Range visibleRange = view->visibleRange();
                KTextEditor::Range intersection = visibleRange.intersect(rangeBelow);
                if (intersection.isValid()) {
                    queueSpellCheckVisibleRange(view, intersection);
                }
            }
        }
    }

    ON_THE_FLY_DEBUG << "finished";
    if (spellCheckInProgress || (emptyAtStart && !m_spellCheckQueue.isEmpty())) {
        QTimer::singleShot(0, this, &KateOnTheFlyChecker::performSpellCheck);
    }
}

void KateOnTheFlyChecker::freeDocument()
{
    ON_THE_FLY_DEBUG;

    // empty the spell check queue
    for (QList<SpellCheckItem>::iterator i = m_spellCheckQueue.begin(); i != m_spellCheckQueue.end();) {
        ON_THE_FLY_DEBUG << "erasing range " << *i;
        KTextEditor::MovingRange *movingRange = (*i).first;
        deleteMovingRangeQuickly(movingRange);
        i = m_spellCheckQueue.erase(i);
    }
    if (m_currentlyCheckedItem != invalidSpellCheckQueueItem()) {
        KTextEditor::MovingRange *movingRange = m_currentlyCheckedItem.first;
        deleteMovingRangeQuickly(movingRange);
    }
    stopCurrentSpellCheck();

    const MisspelledList misspelledList = m_misspelledList; // make a copy!
    for (const MisspelledItem &i : misspelledList) {
        deleteMovingRange(i.first);
    }
    m_misspelledList.clear();
    clearModificationList();
}

void KateOnTheFlyChecker::performSpellCheck()
{
    if (m_currentlyCheckedItem != invalidSpellCheckQueueItem()) {
        ON_THE_FLY_DEBUG << "exited as a check is currently in progress";
        return;
    }
    if (m_spellCheckQueue.isEmpty()) {
        ON_THE_FLY_DEBUG << "exited as there is nothing to do";
        return;
    }
    m_currentlyCheckedItem = m_spellCheckQueue.takeFirst();

    KTextEditor::MovingRange *spellCheckRange = m_currentlyCheckedItem.first;
    const QString &language = m_currentlyCheckedItem.second;
    ON_THE_FLY_DEBUG << "for the range " << *spellCheckRange;
    // clear all the highlights that are currently present in the range that
    // is supposed to be checked
    const MovingRangeList highlightsList = installedMovingRanges(*spellCheckRange); // make a copy!
    deleteMovingRanges(highlightsList);

    m_currentDecToEncOffsetList.clear();
    KTextEditor::DocumentPrivate::OffsetList encToDecOffsetList;
    QString text = m_document->decodeCharacters(*spellCheckRange, m_currentDecToEncOffsetList, encToDecOffsetList);
    ON_THE_FLY_DEBUG << "next spell checking" << text;
    if (text.isEmpty()) { // passing an empty string to Sonnet can lead to a bad allocation exception
        spellCheckDone(); // (bug 225867)
        return;
    }
    if (m_speller.language() != language) {
        m_speller.setLanguage(language);
    }
    if (!m_backgroundChecker) {
        m_backgroundChecker = new Sonnet::BackgroundChecker(m_speller, this);
        connect(m_backgroundChecker, &Sonnet::BackgroundChecker::misspelling, this, &KateOnTheFlyChecker::misspelling);
        connect(m_backgroundChecker, &Sonnet::BackgroundChecker::done, this, &KateOnTheFlyChecker::spellCheckDone);

        KateSpellCheckManager *m_spellCheckManager = KTextEditor::EditorPrivate::self()->spellCheckManager();
        connect(m_spellCheckManager, &KateSpellCheckManager::wordAddedToDictionary, this, &KateOnTheFlyChecker::addToDictionary);
        connect(m_spellCheckManager, &KateSpellCheckManager::wordIgnored, this, &KateOnTheFlyChecker::addToSession);
    }
    m_backgroundChecker->setSpeller(m_speller);
    m_backgroundChecker->setText(text); // don't call 'start()' after this!
}

void KateOnTheFlyChecker::addToDictionary(const QString &word)
{
    if (m_backgroundChecker) {
        m_backgroundChecker->addWordToPersonal(word);
    }
}

void KateOnTheFlyChecker::addToSession(const QString &word)
{
    if (m_backgroundChecker) {
        m_backgroundChecker->addWordToSession(word);
    }
}

void KateOnTheFlyChecker::removeRangeFromEverything(KTextEditor::MovingRange *movingRange)
{
    Q_ASSERT(m_document == movingRange->document());
    ON_THE_FLY_DEBUG << *movingRange << "(" << movingRange << ")";

    if (removeRangeFromModificationList(movingRange)) {
        return; // range was part of the modification queue, so we don't have
        // to look further for it
    }

    if (removeRangeFromSpellCheckQueue(movingRange)) {
        return; // range was part of the spell check queue, so it cannot have been
        // a misspelled range
    }

    for (MisspelledList::iterator i = m_misspelledList.begin(); i != m_misspelledList.end();) {
        if ((*i).first == movingRange) {
            i = m_misspelledList.erase(i);
        } else {
            ++i;
        }
    }
}

bool KateOnTheFlyChecker::removeRangeFromCurrentSpellCheck(KTextEditor::MovingRange *range)
{
    if (m_currentlyCheckedItem != invalidSpellCheckQueueItem() && m_currentlyCheckedItem.first == range) {
        stopCurrentSpellCheck();
        return true;
    }
    return false;
}

void KateOnTheFlyChecker::stopCurrentSpellCheck()
{
    m_currentDecToEncOffsetList.clear();
    m_currentlyCheckedItem = invalidSpellCheckQueueItem();
    if (m_backgroundChecker) {
        m_backgroundChecker->stop();
    }
}

bool KateOnTheFlyChecker::removeRangeFromSpellCheckQueue(KTextEditor::MovingRange *range)
{
    if (removeRangeFromCurrentSpellCheck(range)) {
        if (!m_spellCheckQueue.isEmpty()) {
            QTimer::singleShot(0, this, &KateOnTheFlyChecker::performSpellCheck);
        }
        return true;
    }
    bool found = false;
    for (QList<SpellCheckItem>::iterator i = m_spellCheckQueue.begin(); i != m_spellCheckQueue.end();) {
        if ((*i).first == range) {
            i = m_spellCheckQueue.erase(i);
            found = true;
        } else {
            ++i;
        }
    }
    return found;
}

void KateOnTheFlyChecker::rangeEmpty(KTextEditor::MovingRange *range)
{
    ON_THE_FLY_DEBUG << range->start() << range->end() << "(" << range << ")";
    deleteMovingRange(range);
}

void KateOnTheFlyChecker::rangeInvalid(KTextEditor::MovingRange *range)
{
    ON_THE_FLY_DEBUG << range->start() << range->end() << "(" << range << ")";
    deleteMovingRange(range);
}

/**
 * It is not enough to use 'caret/Entered/ExitedRange' only as the cursor doesn't move when some
 * text has been selected.
 **/
void KateOnTheFlyChecker::caretEnteredRange(KTextEditor::MovingRange *range, KTextEditor::View *view)
{
    KTextEditor::ViewPrivate *kateView = static_cast<KTextEditor::ViewPrivate *>(view);
    kateView->spellingMenu()->caretEnteredMisspelledRange(range);
}

void KateOnTheFlyChecker::caretExitedRange(KTextEditor::MovingRange *range, KTextEditor::View *view)
{
    KTextEditor::ViewPrivate *kateView = static_cast<KTextEditor::ViewPrivate *>(view);
    kateView->spellingMenu()->caretExitedMisspelledRange(range);
}

void KateOnTheFlyChecker::deleteMovingRange(KTextEditor::MovingRange *range)
{
    ON_THE_FLY_DEBUG << range;
    // remove it from all our structures
    removeRangeFromEverything(range);
    range->setFeedback(nullptr);
    const auto views = m_document->views();
    for (KTextEditor::View *view : views) {
        static_cast<KTextEditor::ViewPrivate *>(view)->spellingMenu()->rangeDeleted(range);
    }
    delete (range);
}

void KateOnTheFlyChecker::deleteMovingRanges(const QList<KTextEditor::MovingRange *> &list)
{
    for (KTextEditor::MovingRange *r : list) {
        deleteMovingRange(r);
    }
}

KTextEditor::Range KateOnTheFlyChecker::findWordBoundaries(const KTextEditor::Cursor begin, const KTextEditor::Cursor end)
{
    // FIXME: QTextBoundaryFinder should be ideally used for this, but it is currently
    //        still broken in Qt
    static const QRegularExpression boundaryRegExp(QStringLiteral("\\b"), QRegularExpression::UseUnicodePropertiesOption);
    // handle spell checking of QLatin1String("isn't"), QLatin1String("doesn't"), etc.
    static const QRegularExpression boundaryQuoteRegExp(QStringLiteral("\\b\\w+'\\w*$"), QRegularExpression::UseUnicodePropertiesOption);
    static const QRegularExpression extendedBoundaryRegExp(QStringLiteral("\\W|$"), QRegularExpression::UseUnicodePropertiesOption);
    static const QRegularExpression extendedBoundaryQuoteRegExp(QStringLiteral("^\\w*'\\w+\\b"), QRegularExpression::UseUnicodePropertiesOption); // see above
    KTextEditor::DocumentPrivate::OffsetList decToEncOffsetList;
    KTextEditor::DocumentPrivate::OffsetList encToDecOffsetList;
    const int startLine = begin.line();
    const int startColumn = begin.column();
    KTextEditor::Cursor boundaryStart;
    KTextEditor::Cursor boundaryEnd;
    // first we take care of the start position
    const KTextEditor::Range startLineRange(startLine, 0, startLine, m_document->lineLength(startLine));
    QString decodedLineText = m_document->decodeCharacters(startLineRange, decToEncOffsetList, encToDecOffsetList);
    int translatedColumn = m_document->computePositionWrtOffsets(encToDecOffsetList, startColumn);
    QString text = decodedLineText.mid(0, translatedColumn);
    boundaryStart.setLine(startLine);
    int match = text.lastIndexOf(boundaryQuoteRegExp);
    if (match < 0) {
        match = text.lastIndexOf(boundaryRegExp, -2);
    }
    boundaryStart.setColumn(m_document->computePositionWrtOffsets(decToEncOffsetList, qMax(0, match)));
    // and now the end position
    const int endLine = end.line();
    const int endColumn = end.column();
    if (endLine != startLine) {
        decToEncOffsetList.clear();
        encToDecOffsetList.clear();
        const KTextEditor::Range endLineRange(endLine, 0, endLine, m_document->lineLength(endLine));
        decodedLineText = m_document->decodeCharacters(endLineRange, decToEncOffsetList, encToDecOffsetList);
    }
    translatedColumn = m_document->computePositionWrtOffsets(encToDecOffsetList, endColumn);
    text = decodedLineText.mid(translatedColumn);
    boundaryEnd.setLine(endLine);

    QRegularExpressionMatch reMatch;
    match = text.indexOf(extendedBoundaryQuoteRegExp, 0 /* from */, &reMatch);
    if (match == 0) {
        match = reMatch.capturedLength(0);
    } else {
        match = text.indexOf(extendedBoundaryRegExp);
    }
    boundaryEnd.setColumn(m_document->computePositionWrtOffsets(decToEncOffsetList, translatedColumn + qMax(0, match)));
    return KTextEditor::Range(boundaryStart, boundaryEnd);
}

void KateOnTheFlyChecker::misspelling(const QString &word, int start)
{
    if (m_currentlyCheckedItem == invalidSpellCheckQueueItem()) {
        ON_THE_FLY_DEBUG << "exited as no spell check is taking place";
        return;
    }
    int translatedStart = m_document->computePositionWrtOffsets(m_currentDecToEncOffsetList, start);
    //   ON_THE_FLY_DEBUG << "misspelled " << word
    //                                     << " at line "
    //                                     << *m_currentlyCheckedItem.first
    //                                     << " column " << start;

    KTextEditor::MovingRange *spellCheckRange = m_currentlyCheckedItem.first;
    int line = spellCheckRange->start().line();
    int rangeStart = spellCheckRange->start().column();
    int translatedEnd = m_document->computePositionWrtOffsets(m_currentDecToEncOffsetList, start + word.length());

    KTextEditor::MovingRange *movingRange =
        m_document->newMovingRange(KTextEditor::Range(line, rangeStart + translatedStart, line, rangeStart + translatedEnd));
    movingRange->setFeedback(this);
    KTextEditor::Attribute *attribute = new KTextEditor::Attribute();
    attribute->setUnderlineStyle(QTextCharFormat::SpellCheckUnderline);
    attribute->setUnderlineColor(KateRendererConfig::global()->spellingMistakeLineColor());

    // don't print this range
    movingRange->setAttributeOnlyForViews(true);

    movingRange->setAttribute(KTextEditor::Attribute::Ptr(attribute));
    m_misspelledList.push_back(MisspelledItem(movingRange, m_currentlyCheckedItem.second));

    if (m_backgroundChecker) {
        m_backgroundChecker->continueChecking();
    }
}

void KateOnTheFlyChecker::spellCheckDone()
{
    ON_THE_FLY_DEBUG << "on-the-fly spell check done, queue length " << m_spellCheckQueue.size();
    if (m_currentlyCheckedItem == invalidSpellCheckQueueItem()) {
        return;
    }
    KTextEditor::MovingRange *movingRange = m_currentlyCheckedItem.first;
    stopCurrentSpellCheck();
    deleteMovingRangeQuickly(movingRange);

    if (!m_spellCheckQueue.empty()) {
        QTimer::singleShot(0, this, &KateOnTheFlyChecker::performSpellCheck);
    }
}

QList<KTextEditor::MovingRange *> KateOnTheFlyChecker::installedMovingRanges(KTextEditor::Range range) const
{
    ON_THE_FLY_DEBUG << range;
    MovingRangeList toReturn;

    for (QList<SpellCheckItem>::const_iterator i = m_misspelledList.begin(); i != m_misspelledList.end(); ++i) {
        KTextEditor::MovingRange *movingRange = (*i).first;
        if (movingRange->overlaps(range)) {
            toReturn.push_back(movingRange);
        }
    }
    return toReturn;
}

void KateOnTheFlyChecker::updateConfig()
{
    ON_THE_FLY_DEBUG;
    // m_speller.restore();
}

void KateOnTheFlyChecker::refreshSpellCheck(KTextEditor::Range range)
{
    if (range.isValid()) {
        textInserted(m_document, range);
    } else {
        freeDocument();
        textInserted(m_document, m_document->documentRange());
    }
}

void KateOnTheFlyChecker::addView(KTextEditor::Document *document, KTextEditor::View *view)
{
    Q_ASSERT(document == m_document);
    Q_UNUSED(document);
    ON_THE_FLY_DEBUG;
    auto *viewPrivate = static_cast<KTextEditor::ViewPrivate *>(view);
    connect(viewPrivate, &KTextEditor::ViewPrivate::destroyed, this, &KateOnTheFlyChecker::viewDestroyed);
    connect(viewPrivate, &KTextEditor::ViewPrivate::displayRangeChanged, this, &KateOnTheFlyChecker::restartViewRefreshTimer);
    updateInstalledMovingRanges(static_cast<KTextEditor::ViewPrivate *>(view));
}

void KateOnTheFlyChecker::viewDestroyed(QObject *obj)
{
    ON_THE_FLY_DEBUG;
    KTextEditor::View *view = static_cast<KTextEditor::View *>(obj);
    m_displayRangeMap.erase(view);
}

void KateOnTheFlyChecker::removeView(KTextEditor::View *view)
{
    ON_THE_FLY_DEBUG;
    m_displayRangeMap.erase(view);
}

void KateOnTheFlyChecker::updateInstalledMovingRanges(KTextEditor::ViewPrivate *view)
{
    Q_ASSERT(m_document == view->document());
    ON_THE_FLY_DEBUG;
    KTextEditor::Range oldDisplayRange = m_displayRangeMap[view];

    KTextEditor::Range newDisplayRange = view->visibleRange();
    ON_THE_FLY_DEBUG << "new range: " << newDisplayRange;
    ON_THE_FLY_DEBUG << "old range: " << oldDisplayRange;
    QList<KTextEditor::MovingRange *> toDelete;
    for (const MisspelledItem &item : std::as_const(m_misspelledList)) {
        KTextEditor::MovingRange *movingRange = item.first;
        if (!movingRange->overlaps(newDisplayRange)) {
            bool stillVisible = false;
            const auto views = m_document->views();
            for (KTextEditor::View *it2 : views) {
                KTextEditor::ViewPrivate *view2 = static_cast<KTextEditor::ViewPrivate *>(it2);
                if (view != view2 && movingRange->overlaps(view2->visibleRange())) {
                    stillVisible = true;
                    break;
                }
            }
            if (!stillVisible) {
                toDelete.push_back(movingRange);
            }
        }
    }
    deleteMovingRanges(toDelete);
    m_displayRangeMap[view] = newDisplayRange;
    if (oldDisplayRange.isValid()) {
        bool emptyAtStart = m_spellCheckQueue.empty();
        for (int line = newDisplayRange.end().line(); line >= newDisplayRange.start().line(); --line) {
            if (!oldDisplayRange.containsLine(line)) {
                bool visible = false;
                const auto views = m_document->views();
                for (KTextEditor::View *it2 : views) {
                    KTextEditor::ViewPrivate *view2 = static_cast<KTextEditor::ViewPrivate *>(it2);
                    if (view != view2 && view2->visibleRange().containsLine(line)) {
                        visible = true;
                        break;
                    }
                }
                if (!visible) {
                    queueLineSpellCheck(m_document, line);
                }
            }
        }
        if (emptyAtStart && !m_spellCheckQueue.isEmpty()) {
            QTimer::singleShot(0, this, &KateOnTheFlyChecker::performSpellCheck);
        }
    }
}

void KateOnTheFlyChecker::queueSpellCheckVisibleRange(KTextEditor::Range range)
{
    const QList<KTextEditor::View *> &viewList = m_document->views();
    for (QList<KTextEditor::View *>::const_iterator i = viewList.begin(); i != viewList.end(); ++i) {
        queueSpellCheckVisibleRange(static_cast<KTextEditor::ViewPrivate *>(*i), range);
    }
}

void KateOnTheFlyChecker::queueSpellCheckVisibleRange(KTextEditor::ViewPrivate *view, KTextEditor::Range range)
{
    Q_ASSERT(m_document == view->doc());
    KTextEditor::Range visibleRange = view->visibleRange();
    KTextEditor::Range intersection = visibleRange.intersect(range);
    if (intersection.isEmpty()) {
        return;
    }

    // clear all the highlights that are currently present in the range that
    // is supposed to be checked, necessary due to highlighting
    const MovingRangeList highlightsList = installedMovingRanges(intersection);
    deleteMovingRanges(highlightsList);

    QList<QPair<KTextEditor::Range, QString>> spellCheckRanges =
        KTextEditor::EditorPrivate::self()->spellCheckManager()->spellCheckRanges(m_document, intersection, true);
    // we queue them up in reverse
    QListIterator<QPair<KTextEditor::Range, QString>> i(spellCheckRanges);
    i.toBack();
    while (i.hasPrevious()) {
        QPair<KTextEditor::Range, QString> p = i.previous();
        queueLineSpellCheck(p.first, p.second);
    }
}

void KateOnTheFlyChecker::queueLineSpellCheck(KTextEditor::DocumentPrivate *kateDocument, int line)
{
    const KTextEditor::Range range = KTextEditor::Range(line, 0, line, kateDocument->lineLength(line));
    // clear all the highlights that are currently present in the range that
    // is supposed to be checked, necessary due to highlighting

    const MovingRangeList highlightsList = installedMovingRanges(range);
    deleteMovingRanges(highlightsList);

    QList<QPair<KTextEditor::Range, QString>> spellCheckRanges =
        KTextEditor::EditorPrivate::self()->spellCheckManager()->spellCheckRanges(kateDocument, range, true);
    // we queue them up in reverse
    QListIterator<QPair<KTextEditor::Range, QString>> i(spellCheckRanges);
    i.toBack();
    while (i.hasPrevious()) {
        QPair<KTextEditor::Range, QString> p = i.previous();
        queueLineSpellCheck(p.first, p.second);
    }
}

void KateOnTheFlyChecker::queueLineSpellCheck(KTextEditor::Range range, const QString &dictionary)
{
    ON_THE_FLY_DEBUG << m_document << range;

    Q_ASSERT(range.onSingleLine());

    if (range.isEmpty()) {
        return;
    }

    addToSpellCheckQueue(range, dictionary);
}

void KateOnTheFlyChecker::addToSpellCheckQueue(KTextEditor::Range range, const QString &dictionary)
{
    addToSpellCheckQueue(m_document->newMovingRange(range), dictionary);
}

void KateOnTheFlyChecker::addToSpellCheckQueue(KTextEditor::MovingRange *range, const QString &dictionary)
{
    ON_THE_FLY_DEBUG << m_document << *range << dictionary;

    range->setFeedback(this);

    // if the queue contains a subrange of 'range', we remove that one
    for (QList<SpellCheckItem>::iterator i = m_spellCheckQueue.begin(); i != m_spellCheckQueue.end();) {
        KTextEditor::MovingRange *spellCheckRange = (*i).first;
        if (range->contains(*spellCheckRange)) {
            deleteMovingRangeQuickly(spellCheckRange);
            i = m_spellCheckQueue.erase(i);
        } else {
            ++i;
        }
    }
    // leave 'push_front' here as it is a LIFO queue, i.e. a stack
    m_spellCheckQueue.push_front(SpellCheckItem(range, dictionary));
    ON_THE_FLY_DEBUG << "added" << *range << dictionary << "to the queue, which has a length of" << m_spellCheckQueue.size();
}

void KateOnTheFlyChecker::viewRefreshTimeout()
{
    if (m_refreshView) {
        updateInstalledMovingRanges(m_refreshView);
    }
    m_refreshView = nullptr;
}

void KateOnTheFlyChecker::restartViewRefreshTimer(KTextEditor::ViewPrivate *view)
{
    if (m_refreshView && view != m_refreshView) { // a new view should be refreshed
        updateInstalledMovingRanges(m_refreshView); // so refresh the old one first
    }
    m_refreshView = view;
    m_viewRefreshTimer->start(100);
}

void KateOnTheFlyChecker::deleteMovingRangeQuickly(KTextEditor::MovingRange *range)
{
    range->setFeedback(nullptr);
    const auto views = m_document->views();
    for (KTextEditor::View *view : views) {
        static_cast<KTextEditor::ViewPrivate *>(view)->spellingMenu()->rangeDeleted(range);
    }
    delete (range);
}

void KateOnTheFlyChecker::handleModifiedRanges()
{
    for (const ModificationItem &item : std::as_const(m_modificationList)) {
        KTextEditor::MovingRange *movingRange = item.second;
        KTextEditor::Range range = *movingRange;
        deleteMovingRangeQuickly(movingRange);
        if (item.first == TEXT_INSERTED) {
            handleInsertedText(range);
        } else {
            handleRemovedText(range);
        }
    }
    m_modificationList.clear();
}

bool KateOnTheFlyChecker::removeRangeFromModificationList(KTextEditor::MovingRange *range)
{
    bool found = false;
    for (ModificationList::iterator i = m_modificationList.begin(); i != m_modificationList.end();) {
        ModificationItem item = *i;
        KTextEditor::MovingRange *movingRange = item.second;
        if (movingRange == range) {
            found = true;
            i = m_modificationList.erase(i);
        } else {
            ++i;
        }
    }
    return found;
}

void KateOnTheFlyChecker::clearModificationList()
{
    for (const ModificationItem &item : std::as_const(m_modificationList)) {
        KTextEditor::MovingRange *movingRange = item.second;
        deleteMovingRangeQuickly(movingRange);
    }
    m_modificationList.clear();
}